In the common push button switch used in keyboard device, the rubber dome is used as the actuator. The rubber dome touches against a corresponding switch on the membrane circuit, and actuates the On/Off action of the switch.
To provide a feeling of comfort to the user while the push button switch is depressed, and to prevent a large noise made when the key top touches the top surface of the key top, guide the conventional approaches, using the rubber dome as the actuator, in general, are such that the key top does not impact the top surface of the guide with the rubber dome directly being used to support the key top, as the key top is depressed to its lowest position. However, as the push button switch of this design has been operated over a long time, due to the fact that the rubber dome is overly deformed each time the key top is depressed, as shown in FIG. 6, the rubber dome is easily damaged, shortens the life cycle of the keyboard.